<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>functionName</title>
</head>

<body>
    <div>打开浏览器控制台查看结果</div>
    <script>
        const functionName = handler => (console.debug(handler.name), handler);
        let m = functionName(Math.max)(5, 6);
        // max (logged in debug channel of console)
        // m = 6
    </script>
</body>

</html>